


Past Due

by ACertainZest



Category: Castle (TV 2009)
Genre: Angst, Angst with a Happy Ending, Deal with a Devil, Dogs, F/M, Halloween, Supernatural Elements
Language: English
Status: In-Progress
Published: 2020-11-01
Updated: 2020-11-01
Packaged: 2021-03-08 21:54:18
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 5,007
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27333748
Author URL: https://archiveofourown.org/users/ACertainZest/pseuds/ACertainZest
Summary: After her mother's death, Kate Beckett made a rash decision, which has haunted her for years. When Rick Castle meets her one Halloween night, he's determined to uncover her dark secrets - but little does he know just how deep that darkness runs... (For the 2020 Castle Fanfic Halloween Bash)
Relationships: Kate Beckett/Richard Castle
Kudos: 5





	1. Prologue and Chapter 1

**Author's Note:**

> Hello everyone! Surprise surprise, I'm back with a new story for the 2020 Halloween Bash.
> 
> This story goes a bit darker than my usual, but there is a happy ending, I promise. For those of you who need this to be stated up front - yes there is a dog in this fic, and no, the dog does NOT die.
> 
> Also: I've played fast and loose with the series timeline here, particularly as relates to Alexis's age. Just go with it, k?
> 
> Thanks for reading!

**Prologue**

It's the phone call she has been dreading.

"Katie?"

"Aunt Teresa?" The voice on the other end of the line is tearful and verging on panic. "I - I think I've made a big mistake."

A careful deep breath; she forces her voice to stay calm. "You did it, didn't you? The spell we discussed."

"I know you told me not to," her niece cries. "But I just - I just had to know. And now..." An anguished sob, ripping across the wires to tear at Teresa's heart. "I don't know what I've done."

"Katie, listen to me." Her voice remains calm as a mountain lake, despite the ice of apprehension gripping her throat. "Is it your mother? Is she... back?"

Another sob. "I was going to. But I remembered what you said... about coming back wrong... that it wouldn't really be her."

"That's right." A slight easing of the tension in her chest, cautious relief. "There are some things our family's gifts are not meant for, much though we might desire it."

"I know, but..." In the background a whuffling noise, a quiet whine from a furry throat. "Shh," Katie whispers, muffled, "it's gonna be okay." Then into the phone, "Aunt Teresa, you have to help me. I don't know what happened, what I did, but it's... something isn't right. I don't know what to do."

"We'll figure it out, honey. Is your father there? Put him on the phone."

"I, he's..." A painful pause. "He's... sleeping."

 _Passed out, more like._ Teresa's heart twists again with sorrow for her bereaved brother and his grieving child. "Okay, Katie, okay. Don't worry. Take a deep breath, and tell me everything."

* * *

**Chapter 1**

_(Ten Years Later)_

"Alexis! Where are you?"

Rick Castle moved as quickly as he could through the crowd of adults and kids. He wasn't panicking, he told himself. No. It had only been a moment since he'd lost track of his daughter. He could handle it. She was definitely here... somewhere.

It was an unseasonably warm day for October, and the Halloween party at the playground was in full swing. Parents and costumed kids swarmed, talking and laughing in the glow of the pumpkin-shaped lights that had been strung up all around the little park. Chocolate was everywhere.

Halloween was Rick's favorite holiday, and he had been enjoying himself enormously, up until about a minute ago when he'd noticed that Alexis was no longer visible.

Rick wasn't normally the kind of parent to lose his cool when he couldn't see his kid for a minute; but then, they weren't usually at the playground after dark, and it wasn't usually this crowded.

"Alexis!" he called again, his eyes darting, trying to look everywhere at once.

If Rick hadn't been looking downward, he might not have seen the dog right away; but his attention was directed at child-height, and he stopped short in surprise when his gaze fell onto the animal instead. It was staring directly at him.

It was huge - a big black dog with thickly muscled shoulders and wide paws, its fur shining softly in the early-evening light. Its eyes were dark and focused, looking straight at Rick.

As soon as the dog saw that it had Rick's attention, it came forward, letting out a demanding bark that pierced through the cheerful crowd noise. Rick flinched when the dog opened its jaws and moved toward him, but it didn't hesitate. Those big white teeth took hold of his hand - surprisingly gently - and tugged.

"What? I - what are you doing?" Rick stammered stupidly. What the hell? He was talking to a dog as if it could understand him, as if it could respond. Ridiculous... But... There was a strange glimmer in those deep dark eyes...

Another tug on his hand, more insistent now. Instinct had Rick resisting, trying to pull back, but the dog held on, a whine coming from its throat as it pulled him to one side.

Left with little choice, he took a step toward the dog, and then another as the creature backed away, and then another again. Satisfied, the dog released his hand and turned to continue in the same direction, shooting a glance over its wide shoulder to make sure Rick was still following. To his surprise, he was; he found himself moving after the dog, jostling and zigzagging around other people to keep the animal in sight.

"Wait," he said, again chiding himself for talking to a dog. "Look, I really have to-" But he stopped short as he saw where the dog was leading him.

"Alexis!"

"Daddy!"

Relief flooded through him at the sight of his daughter, whole and unharmed. She was standing with her back pressed against a small tree, and gave the dog a wary look before surging forward and into Rick's arms.

"There you are, pumpkin," he said, exhaling carefully, hugging her firmly, but not too tightly - not enough that she would notice how his hands trembled. "You're fine. Everything's okay."

"I couldn't find you," she said. "But the doggie told me to stay here."

"Told you?" Rick echoed, frowning. He looked down at the dog again. That intensity he'd seen in its eyes was gone, and now it just looked like a perfectly normal - if huge - happy dog, sitting with its tongue lolling out and its tail thumping cheerfully against the ground.

"He pushed me to the tree and made me stay there," Alexis said with a little shrug. "I told him I didn't know where my daddy was, and he made me stay there, and then he went and got you." She tilted her head, regarding the dog with curiosity now that she was safe in Rick's arms. "Do you think he's magic?"

"Maybe," Rick agreed, smiling as the last of his brief panic faded away. "But we should probably find his owner, or-"

"There you are," said a calm voice, and Rick's eyebrows went up as he caught sight of the woman approaching.

She wore a police uniform, but with a pointy black hat perched on top of her head in place of the uniform cap. She walked toward them with the easy, rolling gait of a beat cop, and the dog jumped up instantly, moving to her side to receive a pat on the head and fall into step with her.

"Everything okay over here?" she asked, and although her eyes were in shadow, Rick could feel her looking over him and Alexis, assessing.

"We're fine," Alexis piped up before Rick could respond. "I lost my daddy, and your doggie found him for me."

"Ah." Unsurprised, the cop patted the dog's head again. "That's good. Good boy, Mickey."

"Yes, I'm very grateful, Officer," Rick said, flashing a sheepish smile. "I just took my eyes off Alexis for a minute, and then I couldn't find her in the crowd."

"I'm glad we were here, then," the cop replied, watching as Alexis wriggled out of Rick's arms and back down onto the ground. Bolder now, the little girl approached the dog and gave him a pat of her own. Rick kept an eye on them, still a bit wary, although he was remembering how the dog had taken hold of his hand: insistent, yet doing no damage. Those sharp teeth hadn't even broken the skin.

"I like your costume," the officer was saying to Alexis. "Princess Leia is one of my favorites too."

"She's the best princess," Alexis and Rick said in unison. The cop chuckled softly.

"Yeah, she is," she agreed.

The woman shifted then, so that the light fell on her face for the first time, and Rick's gaze caught hers.

A jolt went through him as their eyes met, and he blinked, feeling the breath momentarily stop in his throat.

Her eyes were deep green, and shadowed in some indefinable way that had nothing to do with the hat on her head or the dark of the night. There was something in those eyes that he couldn't name, but it was pulling at him, irresistible.

The cop held his gaze, her expression cool and composed, giving away nothing. He felt like he could drown in those eyes; like he could spend his whole life trying to solve the mystery that lurked behind them.

Alexis broke into the moment, her little forehead creased as she looked up at the woman. "Are you really a policewoman?"

The cop's expression softened as she turned her attention back to the child. "I'm a witch, see?" she replied, pointing to her witchy hat. But under the bore of Alexis's level stare, she added, "And yes, I'm also a policewoman."

Alexis gave a satisfied nod. "And your doggie helps you fight crime." Solemnly, she addressed the dog. "Thank you for finding my daddy for me."

A wide pink tongue came out and licked Alexis's cheek, making her giggle. "Mickey says you're welcome," the cop translated, her tone serious, although there was a quirk to her lips.

"Mickey is a funny name for a dog," Alexis said. "Isn't it, Daddy? Like Mickey Mouse."

"Yeah, funny," Rick said absently; he was distracted by attempting to catch the woman's eye again, to feel again that strange electric shock that had gone through him when they made eye contact for the first time. But the cop's attention was on the dog, and she wouldn't meet Rick's eyes.

"He's actually named after a baseball player," she said in answer to Alexis, smiling now. "But I do love Mickey Mouse too."

"I like his name. He's a good dog." Alexis gave the dog a final pat and then turned her little face up toward Rick. "Daddy, can we go home now? I'm tired."

"Sure, pumpkin. We need to rest up for trick-or-treating tomorrow anyway," he said, scooping his daughter up into his arms again. But he still couldn't quite tear himself away from the cop, even as she gave them both a nod and reached down to fasten a leash to the dog's collar.

"Have fun tomorrow night," she said to Alexis. And to Rick, still not quite meeting his eyes, eluding his attempt to catch her gaze, she added, "Good night, Mr. Castle."

"Good night," he said, and reluctantly turned away, Alexis already beginning to droop on his shoulder even as she babbled in his ear about candy. He barely heard her words as he moved toward the park's exit, fighting against the urge to turn back.

At the gate, his willpower finally gave out and he paused, swiveling, seeking.

The cop and her dog were walking away, toward the other exit at the far end of the park; but she turned just when Rick did, and their eyes met again across the length of the park, despite the distance and the dark and the crowd, just for a moment.

That same lightning flashed through Rick like a shockwave, making him stumble backward for half a step before he recovered himself.

Then the woman turned away again, and she and her dog melted into the shadows.

It wasn't until much later, after he had tucked Alexis into bed, that Rick realized the woman had called him by name, even though he'd never introduced himself.

And he didn't know her name, nor anything at all about her. All he knew was that he needed to see her again.


	2. Chapter 2

A few weeks later, Rick still had yet to figure out how to track down the mystery cop. But fate (in which he firmly believed) must have been on his side, because when he showed up at his buddy Roy's regular poker game, to his amazement, there she was.

He stopped in his tracks halfway through the door, a greeting to Roy's wife dying on his lips when he caught sight of the woman. She was wearing plain clothes this time, but he would have known her anywhere.

As if she could feel his gaze from halfway across the room, the cop turned fully toward him, their eyes locking again, with that same jolt of ineffable connection he had felt before.

Evelyn Montgomery nudged him out of the doorway to close the door behind him. "Can I take your coat, Rick?"

"Huh?" Manners belatedly kicked in and he tore his gaze away from the young woman, giving Evelyn an apologetic smile. "Right, sorry. Sorry."

"Rick!" Roy Montgomery crossed the room toward him, wearing a big smile. "I forgot to tell you, Bob and the judges have some kind of fundraiser shindig tonight, so I invited some of my best detectives to round out the table." Glancing between Rick and the mystery woman, Roy's gaze sharpened. "Have you and Detective Beckett already met? Kate," he called to her, "you know this clown?"

"Not really, sir," the woman answered, approaching them. "We just met briefly. It's nice to see you again, Mr. Castle," she added politely.

"You too," Rick murmured, momentarily mesmerized all over again by her inscrutable eyes. He forced himself to snap out of it, turning back to Roy to explain. "Yeah, we were at a Halloween party at the park, and I lost sight of my daughter for a minute, and Detective Beckett, uh-" He paused. "Wait, Detective? Not Officer? You were wearing the uniform..."

"Uniform?" Roy repeated, cocking his head curiously.

"Halloween costume," Detective Beckett explained.

"Oh... okay." Rick supposed that made sense, though Roy seemed to find it quite amusing.

"Interesting choice," the captain chuckled.

Beckett shrugged. "It was handy."

"Anyway," Rick went on, "Detective Beckett and her dog helped me track down my kid. I'm very grateful to her and Mickey."

"Mickey?" Roy turned to his detective, looking surprised. "You still have that dog, Beckett? He must be ancient by now. Didn't you already have him when you started at the Academy?"

Beckett's expression was as cool and blank as a new sheet of paper. "He's not as young as he used to be," she said, "but he still gets around fine."

"Hmm," Roy said. He still looked a bit confused, but just then a new group of guests arrived, and it was time for the poker game to begin.

Rick had to make an effort not to stare at Kate Beckett throughout the game. She joked and laughed comfortably with the other cops, and held her own at the table; she won a few big hands, lost a few more, and several times took advantage of Rick's distraction to call his bluffs and take his chips.

He felt lost at sea, dazed and confused. He'd never been so far off his game, so flustered by the mere presence of a woman. There was just something about Beckett ( _Kate_ , he thought over and over, _Kate_ , although the other cops simply called her Beckett), and he hated how vague and banal that sounded; he, a professional writer, author of how many best-selling novels, acclaimed master of the written word, yet the best he could do was there was something about her? It was maddening.

Meanwhile, if she was as affected by him as he was by her, she was doing a damn good job of hiding it - although Rick noticed that she was avoiding eye contact, so subtly he was sure no one else had noticed.

Before long, the evening wore to an end; the cops began to bow out one by one. When Beckett rose, murmuring something about calling it a night, Rick did the same, and kept his tone light and casual when he said, "Walk you out?"

A wry twist to her lips told him that she saw right through him, but she didn't object, and within a moment they had their coats on, walking side by side down the short path from the Montgomerys' front door to the sidewalk.

"I think you got the better of me," Rick said, pushing his hands into his coat pockets. At her lifted eyebrow, he added, "That last hand was my chance to break even, but you pulled it off."

"Ah." She nodded, quirking a half-smile. "Can't be a good cop if you don't know how to bluff."

"Oh. Right."

Rick cleared his suddenly dry throat. He was at a loss for words, and that never happened. It wasn't that he didn't know what came next; of course he did; this was the moment where he would ask Kate for her phone number, maybe even go so far as to ask her out. He had done it dozens of times, with an extremely respectable success rate; he was smooth, he was charming; he knew, in short, how to talk to women.

And yet, here and now, the words wouldn't come. His mind was a blank.

For some reason he was hearing in his mind Kate's voice from that night at the park, the words she had spoken to Alexis: _I'm a witch... I'm also a policewoman_.

He couldn't figure out why that, of all things, was the part that got stuck in his head, here and now.

They passed through the gate onto the sidewalk, and Kate gave him another cool, polite smile. "Goodnight," she said, and turned away.

Wait, Rick thought, the word ringing urgently in his mind, but somehow he couldn't get it past his lips.

She rounded the corner and was gone.

Rick unlocked his car, got in, put on his seatbelt, and sat staring at the darkness beyond the windshield.

"Do you want to grab some dinner some time?" he said aloud to the empty air. "Can I buy you a drink? I'd like to see you again." He groaned and dropped his forehead to the steering wheel. Why were the words coming now, when it was too late?

Sighing, he lifted his head and started the car. As he pulled away from the curb, he heard himself say, "Can I give you a ride home?" He gave out another grunt of frustration and twisted the wheel, zipping back around the corner in the direction Kate had walked. But when his car turned the corner, he saw no sign of her. It was too late.

He sighed again and pointed the car toward home.

* * *

A few days went by, and then stretched into weeks. Rick found himself thinking about Kate Beckett at odd moments: her fathomless eyes, her honey-low voice, the softness on her face when she looked at or talked about her dog.

Every week when he went to Roy's house for poker, he braced himself, wondering if she would be there; but she never was. Every week, he told himself to just ask Roy for her number, it would be that simple; but somehow he never did.

Gina was hounding him for the final edits on _Storm Fall_ , and he often worked late into the night, after Alexis was asleep. And some nights, when he'd had enough of Storm, he closed that window on his computer and switched over to a new one, where he wrote feverishly until the wee hours of the morning, fleshing out a new character. One he couldn't get out of his mind, no matter how hard he tried.

Nikki Heat, he called her, and he strove in vain to bring her to life on the page.

Sometimes, in his dreams, a huge black shape stalked him, muscles rippling in the shadows, thick fur muffling the sounds of its paws on the pavement. But it never attacked.

Christmas passed, his favorite time of year, in a whirlwind of festivities with his mother, daughter, and various friends; and then the dead of winter, and the edits were done, and the promotions for the new book began. There were TV interviews, convention appearances, signings, readings, photo shoots - all carefully scheduled around Alexis's school hours.

Finally, one glittering cold March night, the new book was released, and Kate Beckett came back into his life once again.

"Mr. Castle?" and he spun around, Sharpie in hand, but not lifting it, because as soon as he heard his name from behind him he knew who it was; it was her again, the voice that he would never forget.

"Detective Beckett," he breathed, hoping at the last minute that it had come out charmingly surprised, not desperate. "How nice to see you again."

"Sorry to bother you," she said, and made eye contact hard and fast, no shock of electricity this time: he saw in an instant that this was Kate Beckett in work mode, the depths of her mystery cloaked over with hard purpose. "I need to ask you some questions about a murder that took place earlier tonight."

He blinked in surprise, managed to recover. "Uh... okay, sure. Let me just call the babysitter."

Another surprise when they emerged from the hotel at street level and she led him to her police-issue vehicle: Mickey the dog was sitting in the back seat, tongue lolling. He perked up when he saw them, crowding his bulk into the space between the two front seats, tail wagging.

"Down, Mickey," Beckett said calmly, and the dog subsided, stretching out on the back seat, keeping his eyes on Rick. He felt the back of his neck prickling under that stare.

"You always bring your dog along when you're working?" he asked, studying Beckett's profile as she drove.

"Not always," she answered, which was less than illuminating, and she resisted all his attempts to draw her into small talk until they arrived at her precinct.

When they got out of the car, Mickey stayed behind, calmly lounging with his chin on his paws.

In short order Rick learned that two people had been killed recently, staged to resemble two of his books; it was shocking, distressing, and he agreed immediately to Beckett's request to look at his fan mail. In fact, he pulled out his phone immediately and called Gina, who was still at the release party and pissed off by his sudden departure, but he rolled right over her complaints and made her agree to get the fan mail packed up and sent over first thing in the morning.

* * *

The next few days passed in a whirlwind; Rick had no trouble convincing Roy to allow him to help with the case, although he could see that Beckett was not at all happy about it. She kept her shields up the whole time, her eyes hard and shuttered, no hint of the connection they had made (or he thought they had made) in two previous encounters.

And because she had that armor on, Rick couldn't resist teasing her; he fell easily back into his goofball persona, taking enormous delight in every fleeting twist of her lips that showed he was getting to her. Even when she pinched his nose or ears as punishment, it was worth it; all worth it, to know that she wasn't impervious to him after all.

Before he knew it they had solved the case, working together in tandem; they were in an alleyway, with Harrison Tisdale cornered, and oh yeah, he had a gun to Rick's head, but that was barely a bump in the road as compared to the euphoria of having figured out a real-life murder mystery.

Rick was talking, Harrison was talking, Beckett was pointing her gun at them and trying to maneuver for a shot, when suddenly, out of nowhere, a huge black shape came barreling around the other side of the van, heading straight for the killer's legs.

"Mickey, no!" Beckett shouted, but the momentary distraction was enough to bring Harrison's arm up, the gun pointing to the sky, and Rick operated purely on instinct, his elbow jabbing up into the other man's face, the gun falling into his hands as neatly as if he had choreographed it.

"Tell me you saw that!" he cried exuberantly at Beckett as she surged forward; but Mickey was there first, a low dangerous growl at the back of his throat, slamming both front paws down onto Harrison's back to hold the killer in place while Beckett snatched the handcuffs from Rick.

It would only be many hours later that it occurred to Rick to wonder where the dog had come from. He knew Mickey hadn't been in the car with them on the way over here for the bust, and Beckett's address (which he had finally managed to finagle out of Roy) was halfway across town, so how...? But Beckett hadn't been surprised to see her dog at all. And somehow, in all the chaos of processing the crime scene and handing Harrison over to prison transport, no one else seemed to notice.

As the dust began to settle, Rick found himself at the mouth of the alley again, facing Beckett, who gave him a sardonic smirk and a shake of her head.

"Well," she said, "that's it, Castle, case closed."

 _This doesn't have to be it_ , he heard himself saying in his mind. _We could go to dinner, debrief each other._ But once again, maddeningly, the words wouldn't come to his tongue.

"Yeah," was all he could manage to get out, cursing himself inwardly for the inexplicable loss of his famous cool.

Beckett watched him for a moment as if waiting for him to continue, but when he didn't, she moved her shoulders in a tiny shrug and said, "It was nice working with you, Castle." And she stepped forward, her shoulder brushing his as she passed by him and kept right on walking.

 _Damn it,_ he thought to himself, _it would have been great._

And for just an instant, he could have sworn he heard Beckett's voice resounding inside his head. _You have no idea_ , it whispered.

Giving his head a quick shake as if to expel whatever ghost was lodged in there, he swiveled on his heel to watch her go.

Half a block down the street, he saw the dog again, sitting patiently on his haunches next to Beckett's car. As Castle watched, Mickey stood up, his tail wagging at top speed, to greet Beckett.

Rick saw Beckett pause, and though he couldn't see her face, he detected a certain softness in her body language as she bent over to give Mickey a lingering scratch behind the ears. The dog flicked his head and licked her hand, and Rick caught the corner of her smile as she straightened back up again.

Rick watched her unlock the car, watched the dog and the woman climb in, watched it drive away. And as soon as they were out of sight, he said aloud, "Can I call you sometime? I'd like to be one of your conquests."

"Say what?" asked a voice from his other side. He startled, turned, and found Detectives Esposito and Ryan regarding him with skeptical expressions, for which Rick had to admit he couldn't blame them.

"Uh," he said, "nothing, sorry."

The other men still looked a bit wary, but Ryan said only, "Come on, we'll give you a ride back to the station."

By the time Rick got home, he knew what he needed to do. A few well-placed phone calls to the Mayor, the Commissioner, et cetera, were all it took.

* * *

The next day he showed up at the precinct again, and let Montgomery break the news to Beckett that Rick would be shadowing her for book research. Not surprisingly, she wasn't happy (Rick occasionally enjoyed the rhetorical value of understatement), but she had no choice but to go along. Before he knew it, they were embroiled in a new case: a young nanny found in a clothes dryer.

Rick was fully immersed in the challenge of the case, not to mention the challenge of trying to figure out Beckett. She remained elusive, at some moments seeming to play along with his humor, then at other times thoroughly annoyed by his antics. He couldn't detect any sign of the strange and powerful sparks that he'd felt between them the first few times they'd met, but he continued to flirt, and she continued to pretend (he was pretty sure it was pretend) that she wasn't interested; and so it went.

Until they were standing outside the laundry-room door, watching the killer nanny cut herself with a huge knife, and suddenly it was all much, much too real for Rick. As Beckett opened the door and slipped inside, his writer's brain showed him an extremely vivid picture of what it might look like if Chloe decided to turn that knife on Beckett. Somehow, facing down a teary-eyed young woman with a knife was much more terrifying than being on the wrong end of Harrison Tisdale's gun.

As Rick stood frozen in the doorway, he suddenly felt a nudging against his thigh, and looked down to see Mickey. Just like last time, the dog had appeared out of nowhere, and Rick gaped in astonishment as Mickey gently but firmly pushed him aside, nosed the door open, and slipped into the room.

Beckett never took her eyes off the young woman with the knife, but Mickey moved to stand next to her, his posture protective, putting his huge solid body between Beckett and the knife. And when Beckett finally managed to convince Chloe to drop her weapon, it was Mickey who moved forward first, pushing the knife away with a paw, then gently resting his chin on Chloe's knee. The young woman dropped a hand onto Mickey's massive head, scratching softly, drawing comfort from him even as Beckett was clipping the handcuffs around her other wrist.

As the other cops began to flood into the room, Mickey backed off, quietly padding out of the room. Rick watched him go, still marveling at how the dog had again managed to show up at just the right moment.

He meant to say something to Beckett about it, but somehow it flew out of his head in the chaotic aftermath of the incident, and by the time he remembered, it was too late. Anyway, the case had fired his imagination all the more, so he went home and wrote until the wee hours of the morning.


End file.
